Submission #359246

#	Time	Username	Problem	Language	Result	Execution time	Memory
359246		nicolaalexandra	Shymbulak (IZhO14_shymbulak)	C++14	0 / 100	1583 ms	35692 KiB

shymbulak

/// stiu ca probabil nu e bn
#include <bits/stdc++.h>
#define DIM 200010
using namespace std;

struct segment_tree{
    int maxi,lazy;
    vector <int> v;
} aint[DIM*4];

vector <int> L[DIM];
vector <pair<int,int> > w;
int viz[DIM],fth[DIM],f[DIM],v[DIM],dist[DIM];
pair <int,int> dp[DIM];
int n,i,x,y,k,sol,sol_cnt;

void dfs (int nod, int tata){
    if (k)
        return;

    viz[nod] = 1;
    fth[nod] = tata;
    for (auto vecin : L[nod]){
        if (k)
            return;

        if (!viz[vecin])
            dfs (vecin,nod);
        else {
            if (vecin != tata){
                int x = nod;
                while (x != vecin){
                    v[++k] = x;
                    x = fth[x];
                }
                v[++k] = vecin;
                return;
            }}}}

void dfs2 (int nod, int tata){

    for (auto vecin : L[nod]){
        if (vecin != tata && !f[vecin])
            dfs2 (vecin,nod);
    }

    int maxi = 0, maxi2 = 0, cnt = 0, cnt2 = 0;
    w.clear();
    dp[nod].second = 1;
    for (auto vecin : L[nod]){
        if (vecin == tata || f[vecin])
            continue;

        if (dp[vecin].first + 1 > dp[nod].first){
            dp[nod].first = dp[vecin].first + 1;
            dp[nod].second = dp[vecin].second;
        } else {
            if (dp[vecin].first + 1 == dp[nod].first)
                dp[nod].second += dp[vecin].second;
        }


        w.push_back(make_pair(dp[vecin].first+1,dp[vecin].second));
        /*if (dp[vecin].first + 1 > maxi){
            maxi2 = maxi, cnt2 = cnt;
            maxi = dp[vecin].first + 1, cnt = dp[vecin].second;
        } else {
            if (dp[vecin].first + 1 == maxi)
                cnt += dp[vecin].second;
            else {
                if (dp[vecin].first + 1 > maxi2){
                    maxi2 = dp[vecin].first + 1;
                    cnt2 = dp[vecin].second;
                } else {
                    if (dp[vecin].first + 1 == maxi2)
                        cnt += dp[vecin].second;
                }

            }
        }
        */
    }

    /// verific si drumurile care au lca in nod

    sort (w.begin(),w.end());

    if (w.size() >= 2){
        int val = w.back().first, cnt = w.back().second, nr = 0;
        for (int i=w.size()-2;i>=0;i--){
            if (w[i].first == val){
                nr += cnt * w[i].second;
                cnt += w[i].second;
            } else break;
        }

        if (nr){
            if (val * 2 > sol)
                sol = val * 2, sol_cnt = nr * 2; /// numar perechile de doua ori
            else {
                if (val * 2 == sol)
                    sol_cnt += nr * 2;
            }
        } else {

            int cnt = 0, val = w[w.size()-2].first;
            for (i=w.size()-2;i>=0;i--){
                if (w[i].first == val)
                    cnt += w[i].second;
                else break;
            }

            if (w.back().first + val > sol){
                sol = w.back().first + val;
                sol_cnt = w.back().second * cnt * 2;
            } else {
                if (w.back().first + val == sol)
                    sol_cnt += w.back().second * cnt * 2;
            }}}}

void update_nod (int nod){
    int fiu_st = nod<<1, fiu_dr = (nod<<1)|1;
    if (aint[fiu_st].maxi > aint[fiu_dr].maxi)
        aint[nod] = aint[fiu_st];
    else {
        if (aint[fiu_st].maxi < aint[fiu_dr].maxi)
            aint[nod] = aint[fiu_dr];
        else {
            aint[nod] = aint[fiu_st];
            for (auto it : aint[fiu_dr].v)
                aint[nod].v.push_back(it);
        }}}

void update_lazy (int nod, int st, int dr){
    if (!aint[nod].lazy)
        return;
    if (st != dr){
        int fiu_st = nod<<1, fiu_dr = (nod<<1)|1;
        aint[fiu_st].maxi += aint[nod].lazy;
        aint[fiu_st].lazy += aint[nod].lazy;

        aint[fiu_dr].maxi += aint[nod].lazy;
        aint[fiu_dr].lazy += aint[nod].lazy;
    }
    aint[nod].lazy = 0;
}

void build (int nod, int st, int dr){
    if (st == dr){
        aint[nod].maxi = dist[st];
        aint[nod].v.push_back(st);
        return;
    }
    int mid = (st+dr)>>1;
    build (nod<<1,st,mid);
    build ((nod<<1)|1,mid+1,dr);
    update_nod (nod);
}

void update (int nod, int st, int dr, int x, int y, int val){
    if (x > y)
        return;

    update_lazy (nod,st,dr);
    if (x <= st && dr <= y){
        aint[nod].maxi += val;
        aint[nod].lazy += val;
        update_lazy (nod,st,dr);
        return;
    }
    int mid = (st+dr)>>1;
    if (x <= mid)
        update (nod<<1,st,mid,x,y,val);
    if (y > mid)
        update ((nod<<1)|1,mid+1,dr,x,y,val);
    update_lazy (nod<<1,st,mid);
    update_lazy ((nod<<1)|1,mid+1,dr);

    update_nod (nod);
}

int main (){

    //ifstream cin ("date.in");
    //ofstream cout ("date.out");

    cin>>n;
    for (i=1;i<=n;i++){
        cin>>x>>y;
        L[x].push_back(y);
        L[y].push_back(x);
    }

    dfs (1,0);

    for (i=1;i<=k;i++)
        f[v[i]] = 1;

    for (i=1;i<=k;i++)
        dfs2 (v[i],0);


    /// distantele
    int st = 2, dr = k, nr = 1;
    while (st < dr){
        dist[st] = dist[dr] = nr;
        nr++;
        st++, dr--;
    }

    if (k % 2 == 0)
        dist[st] = nr;

    for (i=1;i<=k;i++)
        dist[i] += dp[v[i]].first;

    /// trb sa retin doua maxime in aint??....

    build (1,1,k);

    if (k % 2){ /// lg ciclu impara => nu pot sa am mai mult de un drum minim intre doua noduri
        int poz = k / 2 + 1;
        for (i=1;i<=k;i++){
            /// query

            for (auto it : aint[1].v){
                if (it == i)
                    continue;

                if (aint[1].maxi + dp[v[i]].first > sol){
                    sol = aint[1].maxi + dp[v[i]].first;
                    sol_cnt = dp[v[i]].second * dp[v[it]].second;
                } else {
                    if (aint[1].maxi + dp[v[i]].first == sol)
                        sol_cnt += dp[v[i]].second * dp[v[it]].second;
                }

            }

            /// update
            if (poz >= k/2 + 1){
                update (1,1,k,i+1,poz,-1);
                update (1,1,k,poz+2,k,1);

                if (poz == k)
                    update (1,1,k,2,i,1);
                else update (1,1,k,1,i,1);
            } else {

                update (1,1,k,i+1,k,-1);
                update (1,1,k,poz+2,i,1);
                update (1,1,k,1,poz,-1);

            }

            poz++;
            if (poz > k)
                poz = 1;
        }
    } else { /// lg para

        int poz = k/2 + 1;
        for (i=1;i<=k;i++){
            /// query

            for (auto it : aint[1].v){
                if (it == i)
                    continue;

                int ok = (it == poz) ? (2) : (1);

                if (aint[1].maxi + dp[v[i]].first > sol){
                    sol = aint[1].maxi + dp[v[i]].first;
                    sol_cnt = dp[v[i]].second * dp[v[it]].second * ok;
                } else {
                    if (aint[1].maxi + dp[v[i]].first == sol)
                        sol_cnt += dp[v[i]].second * dp[v[it]].second * ok;
                }

            }

            /// update
            if (poz >= k/2 + 1){
                update (1,1,k,i+1,poz,-1);
                update (1,1,k,poz+1,n,1);
                update (1,1,k,1,i,1);
            } else {
                update (1,1,k,i+1,n,-1);
                update (1,1,k,poz+1,i,1);
                update (1,1,k,1,poz,-1);
            }

            poz++;
            if (poz > k)
                poz = 1;
        }

    }

    cout<<sol_cnt / 2;


    return 0;
}

Compilation message (stderr)

shymbulak.cpp: In function 'void dfs2(int, int)':
shymbulak.cpp:47:9: warning: unused variable 'maxi' [-Wunused-variable]
   47 |     int maxi = 0, maxi2 = 0, cnt = 0, cnt2 = 0;
      |         ^~~~
shymbulak.cpp:47:19: warning: unused variable 'maxi2' [-Wunused-variable]
   47 |     int maxi = 0, maxi2 = 0, cnt = 0, cnt2 = 0;
      |                   ^~~~~
shymbulak.cpp:47:30: warning: unused variable 'cnt' [-Wunused-variable]
   47 |     int maxi = 0, maxi2 = 0, cnt = 0, cnt2 = 0;
      |                              ^~~
shymbulak.cpp:47:39: warning: unused variable 'cnt2' [-Wunused-variable]
   47 |     int maxi = 0, maxi2 = 0, cnt = 0, cnt2 = 0;
      |                                       ^~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50